PEG–PLA nanoparticles prepared by emulsion solvent diffusion using oil-soluble and water-soluble PEG–PLA

Abstract Poly(ethylene glycol)- block –polylactide (PEG–PLA) nanoparticles were prepared through the oil-in-water (O/W, ethyl acetate/water) emulsion technique using oil-soluble PEG–PLA in the presence of water-soluble PEG–PLA as a surfactant. The particle diameter decreased with increasing water-soluble PEG–PLA concentration, the smallest averaged diameter was 75 nm. From these results, it was found that water-soluble PEG–PLA acted as a surfactant which prevents further coalescence of droplets. In addition, the particles diameter decreased with increasing hydrophile–lipophile balance of oil-soluble PEG–PLA in the absence of water-soluble PEG–PLA. In contrast, the particle diameter was constant in the presence of water-soluble PEG–PLA. Therefore, the capability of water-soluble PEG–PLA as a surfactant was more excellent than that of oil-soluble PEG–PLA.